Crossover from lattice to plasmonic polarons of a spin-polarised electron gas in ferromagnetic EuO


Doped oxides can host a wealth of fascinating physical properties driven by strong many-body interactions, such as the dressing of electrons into polaronic quasiparticles from the interaction with bosonic excitations of the system. Besides the more conventional lattice polarons produced by the coupling to the crystal phonons, plasmonic polarons may form when conduction electrons couple with the collective plasmon excitations of their own Fermi sea. 
Combining angle-resolved photoemission experiments with first-principles calculations, Fabio Caruso, Carla Verdi and Feliciano Giustino, in collaboration with the group of Phil King at the University of St Andrews, report the observation of lattice and plasmonic polarons in the doped ferromagnetic semiconductor EuO. These findings, published in a paper in the journal Nature Communications, suggest interesting opportunities for tailoring charge carrier properties in dilutely doped semiconductors.